File Coverage

blib/lib/Math/BigInt/FastCalc.pm

Criterion	Covered	Total	%
statement	28	33	84.8
branch	4	14	28.5
condition	0	15	0.0
subroutine	8	8	100.0
pod			n/a
total	40	70	57.1

package Math::BigInt::FastCalc;

use 5.006001;
use strict;
use warnings;

use Carp qw< carp croak >;

use Math::BigInt::Calc 1.999801;

BEGIN {
    our @ISA = qw< Math::BigInt::Calc >;
}

our $VERSION = '0.5013';

my $MAX_EXP_F;      # the maximum possible base 10 exponent with "no integer"
my $MAX_EXP_I;      # the maximum possible base 10 exponent with "use integer"
my $BASE_LEN;       # the current base exponent in use
my $USE_INT;        # whether "use integer" is used in the computations

sub _base_len {
    my $class = shift;

    if (@_) {                           # if called as setter ...
        my ($base_len, $use_int) = @_;

        croak "The base length must be a positive integer"
          unless defined($base_len) && $base_len == int($base_len)
                 && $base_len > 0;

        if ( $use_int && ($base_len > $MAX_EXP_I) ||
            !$use_int && ($base_len > $MAX_EXP_F))
        {
            croak "The maximum base length (exponent) is $MAX_EXP_I with",
              " 'use integer' and $MAX_EXP_F without 'use integer'. The",
              " requested settings, a base length of $base_len ",
              $use_int ? "with" : "without", " 'use integer', is invalid.";
        }

        return $class -> SUPER::_base_len($base_len, $use_int);
    }

    return $class -> SUPER::_base_len();
}

BEGIN {

    my @params = Math::BigInt::FastCalc -> SUPER::_base_len();
    $BASE_LEN  = $params[0];
    $MAX_EXP_F = $params[8];
    $MAX_EXP_I = $params[9];

    # With quadmath support it should work with a base length of 17, because the
    # maximum intermediate value used in the computations is less than 2**113.
    # However, for some reason a base length of 17 doesn't work, but trial and
    # error shows that a base length of 15 works for all methods except
    # _is_odd() and _is_even(). These two methods determine whether the least
    # significand component is odd or even by converting it to a UV and do a
    # bitwise & operation. Because of this, we need to limit the base length to
    # what fits inside an UV.

    require Config;
    my $max_exp_i = int(8 * $Config::Config{uvsize} * log(2) / log(10));
    $MAX_EXP_I = $max_exp_i if $max_exp_i < $MAX_EXP_I;
    $MAX_EXP_F = $MAX_EXP_I if $MAX_EXP_I < $MAX_EXP_F;

    ($BASE_LEN, $USE_INT) = $MAX_EXP_I > $MAX_EXP_F ? ($MAX_EXP_I, 1)
                                                    : ($MAX_EXP_F, 0);

    Math::BigInt::FastCalc -> SUPER::_base_len($BASE_LEN, $USE_INT);
}

##############################################################################
# global constants, flags and accessory

# Announce that we are compatible with MBI v1.83 and up. This method has been
# made redundant. Each backend is now a subclass of Math::BigInt::Lib, which
# provides the methods not present in the subclasses.

sub api_version () { 2; }

require XSLoader;
XSLoader::load(__PACKAGE__, $VERSION, Math::BigInt::Calc->_base_len());

##############################################################################

1;

__END__